10 BULLETIN 540, U. S. DEPARTMENT OF AGRICULTURE. 



Correlation. — Physics : Study of conduction, convection, and radia- 

 tion of heat, as applied in the stove. The insulated oven. The 

 tireless cooker. 



Note. — If possible plan an additional lesson on the canning of fruit in which one 

 of the outdoor canners is used in the orchard. In this case can in tin. Show how the 

 culls, which would in many cases be wasted, may be utilized. This work could be 

 given with all the girls in places where large amounts of fruit are available. There 

 might be a contest between the different classes. Aim to emphasize the economic 

 side and at the same time give the girls opportunity to work with large quantities of 

 material. This lesson may be substituted for one of the following lessons or given as 

 an extra lesson on the weekly holiday. 



LESSON 4. 



Problem. — To study the relation of microorganisms to the spoiling 

 of food. 



Points to be brought out. — Since microorganisms which may cause 

 the spoiling of food are present all about us extreme care is necessary 

 to prevent the contamination of food. In preserving we must kill 

 all the microorganisms present or prevent their development. Simple 

 heating at the boiling point for 15 to 20 minutes is sufficient in the 

 case of fruit. Most vegetables are more difficult to sterilize. They 

 must be heated for several hours. A shorter time may be used at a 

 much higher temperature such as is obtained under pressure, or the 

 material may be heated for a shorter time on three successive days. 



References.^— Preservation of Food in the Home, Univ. Mo. Bui., 

 15 (1914), No. 7, pp. 1-8; U. S. Dept. Agr., Farmers' Buls. 359, 426 * 

 and 521. 



Correlation. — English : Stories of germ life. 



LESSON 5. 



Problem. — To can any available vegetables, using the following 

 methods: (1) Cooking on each of three successive days, (2) long 

 cooking at the boiling temperature, and (3) cooking under pressure, 

 if possible. Compare the methods as to time and trouble involved, 

 the keeping qualities of the products, and the amount of fuel required. 



Points to be brought out. — Complete sterilization is more difficult in 

 the case of vegetables than in the case of fruits. The comparative 

 value of the different methods of canning. The canned vegetables 

 are an important addition to the winter's dietary. 



References.— U. S. Dept. Agr., Farmers' Buls. 259*, 1 pp. 30-32; 359. 



Correlation. — Arithmetic: Estimate cost of home-canned vege- 

 tables, taking into consideration the different factors involved. Com- 

 pare with the cost of the factory-canned material. English: His- 

 tory of canning industry (Encyclopedia). 



1 Farmers' Bulletins marked with an asterisk throughout this publication are not available for free dis- 

 tribution, but may be secured from the Superintendent of Documents, Government Printing Office, Wash- 

 ington, D. C, for 5 cents a copy. 



